Ongoing job actions by foreign service officers at about a dozen Canadian missions abroad are increasing visa processing wait times, the federal government says.

The Professional Association of Foreign Service Officers, which represents about 1,350 diplomats, instructed members at some of Canada’s busiest missions to walk off the job last week. The union says its members are paid substantially less than other public servants who do similar work and has been gradually escalating job actions in recent weeks in an effort to convince Treasury Board to return to the bargaining table with a better offer on pay.

Last week, after the federal government returned to the bargaining table with the same pay offer that had been presented earlier, the union ramped up job actions to target some of Canada’s busiest missions and immigration offices abroad. A notice published on the website for the Department of Citizenship and Immigration acknowledged on Tuesday that the job actions have begun to affect the government’s ability to provide services.

“Posted processing times for both temporary and permanent resident visa applications do not take into account work stoppages,” the notice states. “Anyone applying for a visa should anticipate delays and submit their application as far in advance as possible.”

It adds that offices will remain open and provide “at least a minimum level of service.” It says urgent humanitarian applications will be prioritized.

As of Tuesday, diplomats were off work in London, Paris, Mexico, Tel Aviv, Ramallah, Dublin, Hong Kong, and Canada’s delegation to the European Union, according to a union representative. Immigration officers remained off work in Beijing, Shanghai, Delhi and Chandigarh.

Matthew Conway, a spokesman for Treasury Board President Tony Clement, said the government put forward a fair offer for employees and taxpayers. “The Foreign Service is a highly sought after and well-paid posting,” Mr. Conway wrote in an e-mail. “It is unfortunate that the union is attempting to take their labour demands out on Canadians.”

PAFSO president Tim Edwards has said the job actions will result in a significant backlog at immigration processing centres and could infringe on Canada’s trade and investment priorities.

“We are ready and willing to come back as soon as they make a reasonable effort at a fair settlement,” he said on Tuesday.

The union says its members are paid as much as $14,000 less than their counterparts in Canada. It is asking for changes to the Treasury Board’s pay scales for diplomats to bring them up to the same levels as their colleagues who are classified under the commerce or economics division.

Mr. Edwards has said that the union made several concessions in bargaining, including accepting a cap on annual pay increases and the loss of severance for resignations and retirements. The union has been without a contract since June, 2011.